Hey, just thought I would mention, there may be another option....
Can you get hold of some milk and give the smallest ones extra feed? I had to do that when my rabbit had an accidental litter, she became so skinny, I was so worried about her, but after a fortnight of keeping them with mum and me extra feeding twice a day, all was fine. They had the benefit of snuggles with bros and sis's and hopefully some milk off mum as well as a bit extra few to them by me.
I think people generally recommend goats milk these days? I used lactose free powder milk back in the day (it was 8 years ago).
Also, you can buy hand rearing teats.... I think Mikki do one, you might be able to buy one at the vets maybe
PM is you want any extra help. Good luck!! (ps, give the babies that are the smallest and weakest a bit more when you feed them
)